Ankle X-ray

What it is

The ankle is a socket: the lower ends of the shin bones form an arch over the top of the talus, held together by ligaments on each side. When someone rolls an ankle, the swelling and pain that follow do not tell you whether a ligament stretched or a bone cracked. An x-ray does, because bone absorbs the beam and shows up white while the soft tissue around it does not. Images are taken from several angles — the front, the side, and an angled view that opens up the joint space — because a fracture line invisible on one projection is often obvious on another. The same films also show whether the bones have shifted out of their normal relationship, which matters more for treatment than the crack itself.

Why it is done

• To tell a fracture from a sprain after a fall, a twist, or a sports injury, when the examination cannot separate them
• To check whether the ankle joint has widened or the bones have shifted, which changes how a break is treated
• To look for a chip of bone pulled off by a ligament at the moment of injury
• To follow a known fracture through healing, or to check alignment after a cast or a surgical repair
• To assess long-standing ankle pain for arthritis, old injury, or loose fragments in the joint

What to expect

The technologist positions the foot and ankle on the plate, usually asking for the leg to be rotated a set amount between shots, and steps behind a screen for each exposure. Each image takes a moment; the whole visit is typically five to ten minutes once you are in the room. It is painless in itself, though moving an acutely injured ankle into position can hurt. There is no preparation and nothing to recover from. In an emergency department the treating clinician often looks at the images immediately, but a radiologist reviews them formally afterward and that reading is the official report.

Questions worth asking

• How many views were taken? Ankle x-rays are coded by the number of projections, and a two-view study and a fuller series are different charges.
• Where is this being done — an emergency department, an urgent care clinic, or an orthopaedic office? For the same films, the facility charge differs enormously between them.
• Will follow-up films during casting or healing each be billed as a new x-ray?
• Is the radiologist's formal reading billed separately from the emergency physician's or orthopaedist's own look at the images?
• If both the ankle and the foot are filmed, are those two codes? They are adjacent but separately billed studies.